The invention is based on a wiper system as.
Wiper systems, especially for motor vehicles, are secured to the motor vehicle body and substantially comprise a wiper drive, which via a drive shaft and rod linkage drives power takeoff shafts, which are supported in wiper bearings that protrude from the vehicle body and onto which wipers are placed.
The wiper drive comprises a wiper motor and a gear, whose gearbox has a bearing support, in which an outward-protruding drive shaft is guided. The wiper drive must be fixed in the axial and circumferential directions so that the reaction forces of the torque to be transmitted and the forces of gravity can be absorbed. From European Patent Disclosure EP 409 944 B1, a wiper system is known that is secured by a receptacle for the wiper drive to the body of the motor vehicle. The wiper drive is connected to the receptacle via three threaded joint legs disposed in a triangle about the bearing support, or else is integrally formed onto the gearbox. The receptacle is adjoined at the side by tubular carriers for the wiper bearings. They are slipped onto projections and form-lockingly joined to them, preferably by being snapped into recesses. The snap placement creates an inseparable connection. In wiper systems with two wiper bearings, two tubular carriers are also needed, which are joined to the receptacle or the gearbox via two interfaces.
A wiper system with a tubular carrier on which two wiper bearings can be secured is also known from the prior art. The receptacle for the wiper drive is welded to the tubular carrier. The wiper drive is secured in turn to the receptacle with three threaded joint legs disposed in a triangle about the bearing support.
The embodiment according to the invention as has the advantage that two wiper bearings can be disposed on one tubular carrier, so that the receptacle is connected form- and/or force-lockingly to the tubular carrier by only one interface. The result is attained is lightweight, compact connections which in most versions are at the same time separable again, and which can be monitored economically and easily. The materials are joined together without the addition of heat, so that any hardening, changes in the microstructure, or embrittlement that might be caused thereby are precluded. Materials of different kinds can be easily joined to one another. The parts can be mounted using simple tools.
In addition, reject parts are reduced, because the connection can be undone again to correct assembly errors or for replacement of defective parts. One receptacle can be used for different tubular carriers, and the wiper system can be adapted to different built-in variations, in that the receptacle is slipped onto the tubular carrier and/or rotated about angular ranges that are specified by the form-locking contour.
In the automotive industry, economizing a weight with the attendant fuel savings are especially important today. Even slight economies in many small individual components are important, because they reduce the total weight considerably directly as well as indirectly by smaller dimensioning of the adjoining components. According to the invention, the tubular carrier is made by an internal high-pressure process (IHV), and as a result it can be made hollow, stiff, relatively thin-walled, and thus especially light in weight.
In principle, both a purely form-locking and a purely force-locking connection are conceivable. Preferably, however, the two types of connection are used in combination, so that on the one hand strong forces and moments can be absorbed by the form lock and on the other freedom in terms of play can be attained because of the force lock. According to the invention, the form lock is attained in the circumferential direction with a nonround form of the tubular carrier and a suitable outer contour of the receptacle, such as a contour other than the circular, such as polygonal or in some other way, regular or irregular, elliptical, or with sets of teeth. In the longitudinal direction, a force-locking connection often suffices. If major forces must be absorbed in the longitudinal direction as well, however, then a form lock can additionally be attained by means of a contour, dimension or orientation of the tubular carrier that varies in the longitudinal direction.
A further contribution to a compact, lightweight mode of construction is made by a receptacle that is formed entirely or in part onto the gearbox. Interfaces, individual parts, and thus assembly effort and expense as well as weight can thus be reduced.
Simple assembly is especially important in large-scale production. Simple assembly is attained according to the invention with a tubular carrier that is placed in an indentation in the receptacle in form-locking fashion in the longitudinal direction and/or the circumferential direction and then fixed force-lockingly with a clip that closes the indentation. In special cases, for instance under heavy load, an additional form-locking connection between the clip and the tubular carrier may be appropriate.
If an indentation is formed in part or entirely by one or more fastening regions of the gearbox that are embodied as threaded joint legs, and if the screw thereof is used for the force lock with the clip, then existing components are assigned additional functions, while additional components are avoided, thus saving weight and space. A further contribution in this respect is made by a clip screwed onto only one side which on the other side is suspended form-lockingly from the gearbox or the receptacle. A clip of this kind can be installed and removed quickly.
The number of interfaces can also be reduced by means of receptacles formed entirely on the gearbox. In a feature of the invention, this is attained with receiving faces that are formed onto the feet of what are preferably two threaded joint legs. The tubular carrier is fixed force-lockingly, and possibly form-lockingly as well, in the receiving faces. To this end, it has openings or stepped bores through which the threaded joint legs are inserted. The force lock is created with the screws of the threaded joint legs with which the tubular carrier is pressed into the receiving faces. The result is a very compact, lightweight construction with only a few components. To distribute the clamping force uniformly over the tubular carrier and to attain good guidance, a reinforcing shell may be placed between the screws and the tubular carrier. In particular, the clamping force can be better distributed and advantageous centering can be attained without any additional element, by forming conical supports onto the tubular carrier, preferably by means of an internal high-pressure process, the supports then form-lockingly adjoining suitably shaped threaded joint legs. Formed-on supports can also be utilized to center the tubular carrier in the receiving faces. Better guidance and force distribution can also be attained with a larger pitch circle of the threaded joint legs, because then the spacing between the force introduction points is increases.
It is often advantageous for work operations to be integrated into existing method steps in manufacture. This allows a considerable reduction in the effort and expense of assembly and in the number of interfaces. According to the invention, this is achieved with an internal high-pressure process. To that end, a stamped/bent component which has shells placed high and low is preferably used as the receptacle. A still round tubular carrier is thrust through the shells and then placed in an internal high-pressure-process tool with the receptacle. The tubular carrier is then acted upon by pressure, which causes it to pressure together with the shells against the inner wall of the internal high-pressure-process tool. The inner wall is preferably nonround, so that a form lock is attained in the circumferential direction between the receptacle and the tubular carrier. The shells can be preshaped in nonround fashion from the outset, to suit the inner contour of the internal high-pressure-process tool. Preferably, they are preshaped enough that by means of a joint deforming operation a durable form- and force-locking connection is created between the tubular carrier and the shells, without having to employ excessive forces, because of the accumulation of material.